Electronic tube



March 7, 1961 H. KATZ 2,974,250

ELECTRONIC TUBE Filed Feb. 4, 1955 INVENTOR.

United States ELECTRONIC TUBE Helmut Katz, Munich, Germany, assignor to Siemens &

Halske Aktiengesellschaft, Munich and Berlin, Germany, a corporation of Germany This invention is concerned with an electronic tube, especially a tube for high-frequency work.

In electronic tubes and especially in tubes opera-ting within a high-frequency range, it is frequently necessary to keep the lead-in inductances to the electrodes small. This is in known manner obtained by using lead-in conductors with large surfaces. However, this type of leadin conductor produces difficulties when used for an electrode, for example, a cathode that has to be held at elevated temperature. If the usual materials having high electrical conductivity are in such a case used for a lead-in conductor with a large surface, the corresponding high heat conductivity will cause an undesirably great heat loss at the corresponding electrode. In the case of a cathode, it may accordingly happen that the temperature distribution along the cathode surface becomes unfavorable; in most cases, however, it will be necessary to increase the heating requirements to an intolerable value.

In order to avoid these difliculties, the invention proposes to make the lead-in conductors for electrodes that have to be kept at elevated temperatures, especially for cathodes, in the form of ribbons or the like, having a large surface, and made of a material having relatively low heat conductivity. The invention is applicable for ribbon-shaped lead-in conductors as well as conductors of this kind having tubular or similar configuration. The material may be a suitable alloy with suflicient thermal strength containing preponderantly nickel, chromium and molybdenum. Especially suitable is an alloy known under the trade name Contracid B7M containing primarily nickel, chromium and molybdenum.

The lead-in structure is suitably formed so that its thickness is extraordinarily small as compared with its width or other lateral dimensions. Especially suitable are, for example, ribbons with a thickness of about to [.L. It may be suitable to form the ribbons as thin as possible consistent with the requirements of mechanical strength. The surface may then be increased to any practically desirable value by increasing the width of the corresponding ribbon. It is particularly advantageous to make the ribbon width correspond substantially to the width of the cathode.

The heat conductivity of the previously noted alloy is at 0.025 kal./cm. sec. degrees smaller than that of Invar whose value is at the temperature ranges to be considered generally about 0.03 kal./cm. sec. degrees. Such or a similar alloy is particularly suitable on account of its nonmagnetic properties, as compared with Invar which is oftentimes magnetizable.

The invention will now be described with reference to the accompanying drawing showing an embodiment with parts in simplified schematic representation.

So far as the envelope of the tube is concerned, the drawing merely shows the tube inlet part 1 formed by a pressed glass member. The nine lead-in members 2 to 10 operating as prongs are fused in the part 1. The cathode is indicated by numeral 11; it is oval and covered on its wide sides with an emissive material. The

lead-in conductors 12 and 13 are made in the form of. thin ribbons with a thickness of 10 to 15 ,u. and made of a material of low thermal conductivity. The width of, the ribbon which is substantially the same along all points correspondsv approximately to the widthofthe emitting surfaces of the cathode 11. The lead-in ribbons 12 and 13 are connected with prongs 5' and 7 by welding or the like.

Changes may be made within the scope and spirit of the appended claims.

I claim:

1. An electronic high-frequency discharge device including a cathode operating at relatively high temperature comprising oppositely arranged emitting surfaces, lead-in members, lead-in conductors operatively connected to said emitting surfaces and to said lead-in members, said lead-in conductors comprising a nonmagnetic alloy of metals of the group consisting of nickel, chromium and molybdenum, said alloy possessing low inductance and low thermal conductivity not exceeding 0.03 kal./cm. sec. degrees and remaining substantially constant within a relatively wide temperature range extending beyond the operating temperature of said cathode, and said width of said lead-in conductors substantially the predetermined width of said oppositely arranged emitting surfaces of said cathode.

2. An electronic high-frequency discharge device including a cathode operating at relatively high temperature comprising'oppositely arranged emitting surfaces, lead-in members, ribbon-shaped lead-in conductors operatively connected to said emitting surfaces and to said lead-in members, said lead-in conductors comprising a non-magnetic alloy from two or more metals of the group consisting of nickel, chromium and molybdenum, said alloy possessing low inductance and low thermal conductivity not exceeding 0.03 kaL/ cm. sec. degrees and remaining constant within a relatively wide temperature range extending beyond the operating temperature of said cathode, said Width of said ribbon-shaped lead-in conductors substantially the predetermined width of said oppositely arranged emitting surfaces of said cathode,.each of said ribbon-shaped lead-in conductors having a thickness relatively small as compared with its width, and each of said ribbon-shaped lead-in conductors having a thickness within the range of from substantially 10 to 15 IL.

3. A lead-in conductor for an electronic high-frequency discharge device including a cathode comprising an emitting surface and a lead-in member, said lead-in'con-,-

ductor adapted for operatively connecting one end to the emitting surface and the other end to the. lead-in member, said lead-in conductor formed of a non-magnetic alloy of metals of the group consisting of nickel, chromium and molybdenum, said alloy possessing low inductance and low thermal conductivity not exceeding 0.03 kal./cm. sec. degrees and remaining substantially constant within a relatively wide temperature range extending beyond the operating temperature range extending beyond the operating temperature of said cathode, and said width of said lead-in wire conductors substantially the predetermined width of said emitting surface of said cathode.

'4. A ribbon-shaped lead-in conductor for an electronic high-frequency discharge device including a cathode comprising an emitting surface and a lead-in member, saidv ribbon-shaped lead-in conductor adapted for operatively connecting one end to the emitting surface and the other" end to the lead-in member, said ribbon-shaped lead-in conductor formed of a non-magnetic alloy from two or I and low thermal conductivity not exceeding 0.03 kaL/cm.

sec. degrees and remaining constant within a relatively wide temperature range extending beyond the operating temperature of said cathode, said width of said ribbonshaped lead-in conductor substantially the predetermined width of said emitting surface of said cathode, said ribbon-shaped lead-in conductor having a thickness relatively small as compared with its width, and said ribbonshaped lead-in conductor having a thickness within the range of from substantially 10 p to 15 1..

References Cited in the file of this patent UNITED STATES PATENTS Diehl May 1, 1883 Langmuir July 23, 1918 Schulte June 4, 1940 Norton May 24, 1949 Fulton Jan. 2, 1951 Sorg et a1. July 28, 1953 

